Notice of Land and FresJiwater Shells. 3 



tooth; peristome white, or reddish horn colored, thickened, 

 expanded, and roundly reflected, with two teeth on the margin 

 of the callus, the lower one lamelliform, the other small, often 

 obsolete, the columellar margin partially covering the middling 

 sized pervious umbilicus. 



Diam. maj. 13|-, min. 11, Alt. Y mill. 



Station. — Under logs and in dry pine woods. 



Habitat. — Dead specimens found near Coeur d'Alene Mis- 

 sion, Coeur d'Alene Mountains ; — living ones on the west side 

 of the Bitter Root Mountains, Washington Territory, J. G. 

 Cooper ! ; St. Joseph's Eiver, 1st Camp, Oregon, Cabinet of W. 

 G. Binney. 



Remarks. — This species is most nearly allied in form to H. 

 Golumhiana Lea* {H. labiosa Gould), the peristome is however 

 not only more thickened, but also singularly reflected behind the 

 plane of the aperture, producing a canal behind it, leading from 

 the upper margin into the umbilicus. Being tridentate it has 

 some alliance with H. tridentata Say, but that shell is of coarser 

 texture, more depressed, has a more open umbilicus, and the 

 form of the peristome and teeth are different. 



Dr. Cooper found a beautiful hyaline specimen under a stone 

 '' by the Bitter E-oot River, at an elevation of 4000 feet, on a hill 

 called ' Half Way ' 30 miles below the junction." This 

 variety is much depressed, translucent, delicately striated, and 

 has the parietal tooth only. The very thin epidermis shows the 

 spiral lines, and the last whorl numerous scars of the tubercles 

 mentioned in our description of the species. In Mr. Binney's 

 specimen from Oregon the umbilicus is wider, and not so much 

 covered by the peristome as in the other examples. 



The species is named in honor of Lieutenant Mullan, U.S.A., 

 who has done much in collecting the natural products" of the 

 region in which it was found. 



* A specimen of //. Columbiana Lea in the Cabinet of T. Bland, has a -well de- 

 reloped parietal tooth, the same as in H, thyroides Say. 



